Method of and apparatus for the deburring of workpieces

ABSTRACT

Apparatus for the electrochemical deburring of metallic workpieces in which a drum of endless band forms a continuously displaceable surface for the workpieces which, together with carbon particles and/or other abrasive particles, are agitated in an electrolyte. The drum is rotated about its horizontal axis while a pair of disks form electrodes closing the drum. When the endless belt is used, it then passes into a vessel retaining the electrolyte and thereafter carrying the workpieces to a collecting trough while carbon particles are continuously added or removed from the system whose electrodes are connected in pair to respective phases of the power supply. A drum system may also have a perforated-wall drum or other means for enabling gases to be withdrawn from the system while a stationary vessel system may effect the agitation of the electrolyte by pulsed jets. A gas is injected into the electrolyte to distribute the electric current path more uniformly and dilute nascent gases produced by electrolysis.

United States Patent inventor Appl. No. Filed Patented Priorities METHODOF AND APPARATUS FOR THE DEBURRING 0F WORKPIECES 13 Claims, 11 DrawingFigs.

US. Cl 204/202, 204/213, 204/199, 204/198, 204/201 Int. Cl 801k 3/00,C23b 3/00, C23b 3/06 Field of Search 204/2 12, 213, 214, 201, 204, 202,203, 205, 200; 134/120. 121,1S9;259/89;51/163. 13; 118/418. 602

Primary ExaminerJohn H. Mack Assistant Examiner-A. C PrescottAttorney-Karl F. Ross ABSTRACT: Apparatus for the electrochemicaldeburring of metallic workpieces in which a drum of endless band forms acontinuously displaeeable surface for the workpieces which, togetherwith carbon particles and/or other abrasive particles, are agitated inan electrolyte. The drum is rotated about its horizontal axis while apair of disks form electrodes closing the drum. When the endless belt isused, it then passes into a vessel retaining the electrolyte andthereafter carrying the workpieces to a collecting trough while carbonparticles are continuously added or removed from the system whoseelectrodes are connected in pair to respective phases of the powersupply. A drum system may also have a perforated-wall drum or othermeans for enabling gases to be withdrawn from the system while astationary vessel system may effect the agitation of the electrolyte bypulsed jets. A gas is injected into .the electrolyte to distribute theelectric current path more uniformly and dilute nascent gases producedby electrolysis.

PATENTED 16 3, 620 953 SHEET 2 [IF 6 FIG.4

KIYOSHI INOUE INVENTOR.

BY ma l :RO

ATTORNEY PATENTEmmv 16 I97! 3, 520,953

sum 3 0F 6 FIG.5

KIYOSHI INOUE INVENTOR.

ATTO RNEY PATENTEUHBV 18 I9" 3,620 953 SHEET 0F 6 FlG.6

KIYOSHI INOUE INVENTOR.

Karl

ATTORNEY PATENTEUNUV 1 6 I9?! SHEET 5 BF 6 nnn FIG

KIYOSHI INOUE INVENTOR.

BY {Karl 2 ATTORNEY which is a continuation-in-part of application Ser.No.

598,391 filed 1 Dec. 1966.

My present inventionielaTes to a method Stand an a paratus for thedeburring of metallic and other conductive workpieces whereby surfaceirregularities of such workpieces are eliminated.

Deburring apparatus of several types are commonly in use in themetal-working field, primarily for the removal of surface irregularitiesin cast, machined and molded metallic workpieces. For the most part,such apparatus includes a tumbling drum provided with agitating meansfor repeatedly casting the workpieces, generally in a liquid vehicle andsometimes in the presence of an abrasive, into contact with one another,against the walls of the vessel or drum or into contact with otherbodies (e.g. of abrasive material) mixed with the charge in the drum.This tumbling action mechanically dislodges adherent materials whilerounding off irregular por tions and projections integral with themetallic bodies. These systems, however, are relatively slow and evendefective when the deburring operation is to remove substantial amountsof material.

It is, therefore, the principal object of the present invention toextend principles originally set forth in the above-identified copendingapplication and to provide a method of deburring metal workpieceswhereby the rate of material removal and the surface finish of thetreated objects is significantly increased and improved.

Another object of this invention is to provide relatively simple andinexpensive apparatus for a high rate deburring of metallic workpieceswhile yielding a relatively high-quality surface finish.

Yet another object of this invention is to provide a method of and anapparatus for the deburring of relatively largedimension workpieces ofsuch nature that tumbling may be impractical.

These objects and others which will become apparent hereinafter areattained, in accordance with the present invention, by a method ofdeburring metallic workpieces in which the liquid vehicle is agitated incontact with the workpiece to be deburred while mechanical contactbetween the surfaces of the latter and at least some other bodies iscarried out concurrently with an electrochemical material-removal step.As set forth in application Ser. No. 598,391, l have found,surprisingly, that electrochemical techniques hitherto used primarilyfor the electrochemical machining (ECM) and electrochemical grinding(ECG) of metallic bodies, wherein close tolerances are a necessity, canbe used effectively in conjunction with a tumbling or agitatingoperation to debur metallic workpieces or objects havingelectrolytically soluble surface portions. The surprising nature of thisdiscovery will become all the more apparent when it is recognized thatthe present method does not require a stationary electrode urged againstthe workpiece or juxtaposed therewith via a predetermined machining gap.

In accordance with the principal feature of this invention, anelectrochemical machining current, which may be direct or periodic (e.g.raw-rectified alternating current, pulsating direct current and ordinaryAC) is passed through the liquid vehicle which is constituted as anelectrolyte and may contain abrasive particles or merely additionalbodies to facilitate mechanical deburring of the workpieces concurrentlywith the electrochemical action. While, in some cases, the workpiece maybe stationary and is connected with a pole of the electrochemicalmachining sources, 1 have found that it is not necessary to connect theworkpieces directly thereto, and that the more tumbling of suchworkpieces in an electrolyte and in a drum having spaced-apart contactportions bridged by the electrolyte but not shortcircuited by the drumitself, can effect electrochemical removal of material from theworkpiece surfaces.

While I do not wish to be bound by any theory in this regard and theprecise reasons why the current flow through the electrolyte iseffective to remove material from the surfaces of the conductiveworkpieces are not yet clear, it may be hypothesized that each of theworkpieces acts as an electrode for the machining of others or asobjects undergoing electrolytic erosion against other conductive bodies.Since electrolytic oxidation of the workpiece at its surface isessentially nonreversible in the sense that agitation and mechanicalaction of the electrolyte carries away the oxide film as soon as it isformed and, even upon electrical (polarity) reversal, metal is notmaterially redeposited from the oxide onto the machine surface, theelectrolytic action is carried out as if a wire were directly connectedto each workpiece.

According to a more specific feature of this invention, the agitation ofa multiplicity of workpieces is effected in a tumbling drum which may beprovided at its base with one electrode portion and with a secondcontact or electrode, at a location spaced therefrom but in contact withthe electrolyte, the electrodes being connected across an AC or DCelectrochemical-machining source e.g. of the type described andillustrated in any of my copending applications Ser. No. 512,338, (U.S.Pat. No. 3,475,512) Ser. No. 535,268, (U.S. Pat. No. 3,417,006) Ser. No.562,857, No. 3,420,759) filed 8 Dec. 1965, 19 Jan. 1966 and 5 July 1966,respectively. The tumbling drum can be upwardly open and rotatable aboutan axis tilted upwardly at an angle of, say, 30 degrees from thehorizontal. In this case, the agitation is effected purely by rotationof the drum.

l have also found it to be possible, in conjunction with such a tumblingdrum, or when a stationary vessel is employed, to effect the agitationat least in part by magnetic means. Thus, if the workpieces treated inthe deburring operation or the other bodies involved are magneticallypermeable, I apply a magnetic field to them so as to effect theirdisplacement in the electrolyte. 1 also may distribute in the deburringvessel among the workpieces, particles or bodies of a magneticallypermeable material. Such bodies may be abrasive or electricallyconductive to facilitate electrochemical erosion of the workpieces orproduce the friction necessary for the deburring action. In fact, theparticles or bodies serving as the agitating means need not bemagnetically permeable under some circumstances, since the particles inthe electrolyte tend to respond to a rapidly changing magnetic field byrotating about the axis thereof. Thus, agitation may be promoted withthe aid of conductive as well as magnetically permeable particles.According to still another feature of this aspect of the invention, theparticles which are magnetically or electrically displaceable in theliquid vehicle, can be coated with abrasive material, incorporated in ormixed with abrasive particles which are not influenced by anelectromagnetic field.

Preference is given, in accordance with this invention, to pulsating oralternating electromagnetic fields for controlling the movement ofparticles and inducing electrochemical erosion of the workpiece surfacessince purely direct current has a tendency to produce agglomeration ofmagnetic particles in the deburring vessel.

According to another aspect of the basic invention, more fully describedin application Ser. No. 598,391, the agitation is carried out byrotating an electrode immersed in the electrolyte by, for example,rotating an electrode member in an irregular die cavity to deburr themachined surfaces thereof. Abrasive particles are here included in thedeburring vehicle while an electrolytic machining current is appliedbetween the workpiece and this rotating element. Inasmuch as thiselectrode member is not closely juxtaposed with the workpiece surfaceand is rotated relatively rapidly, a more or less uniform surfacing iseffected. In accordance with this aspect of the invention, I prefer toincorporate in the vehicle a multiplicity of conductive particles whichhere act as intermediate electrodes and as they are dispersed by theagitation into the rotation of the die surfaces, each particle acts asan individual electrode to facilitate smoothing of the die surface. Therotary electrode member imparts a centrifugal force to the abrasive andconductive particles contained within the electrolyte so that theseparticles are dynamically urged outwardly and forcefully brought intocontact or close juxtaposition with the surfaces to be treated toaugment the resulting mechanical deburring action.

According to yet another aspect of this invention, deburring is carriedout as augmented by a magnetic field pressure which, when combined withthe dynamic flow of rapidly moving particles, with the centrifugal forceof tumbling or electrolyte displacement by a stirrer and withgravitational forces, magnetically urges the abrasive bodies against theworkpieces and the workpieces against one another. This magnetic fieldpressure is, advantageously, supplied by electromagnetic means disposedexternally of the deburring vessel and capable of applying inwardmagnetic forces to the magnetically permeable particles and workpieces.When the abrasive particles or auxiliary bodies serving to facilitatemechanical removal of irregularities and projections upon the workpiecesare magnetically permeable and/or the workpieces are of suchpermeability, a high frequency magnetic field applied from without, inaccordance with this invention, induces an oscillation and/or amagnetostrictive expansion and contraction of the bodies so that thesimple tumbling action is accompanied by a magnetic vibration orpulsation of the body to improve the erosive operation. In thisconnection it can also be stated that the field may be of such naturethat vibration of the individual particles by the magnetic field iscoupled with a tumbling action of a rotary drum or a vibration thereofto increase the mechanical abrasion.

Another feature of this invention resides in the use of chemical actionin removing surface irregularities in combination with theelectrochemical and mechanical deburring action as described above. ThusI have found that surprisingly effective results can be obtained when achemical mordant or etchant for the workpiece material is incorporatedin the electrolyte. For as yet unknown reasons, the surface finish anddeburring rate obtained when, for example, ferric chloride is used asthe chemical etchant in the electrolyte, is better than that which wouldbe expected with either the etchant or the electrochemical action alone,while the rate of material removal exceeds the sum predictable from theindividual actions of the etchant and the electrochemical erosion.

According to a further feature of the present invention, theelectrochemical deburring of metallic workpieces is carried outconcurrently with agitation of the bodies in an electricallynonconductivc tumbling drum rotatable about a recumbent axis (preferablyhorizontal or near horizontal) containing liquid electrolyte and theconductive (i.e. carbon) particles, together with the workpieces asdescribed therein. A pair of electrodes are in constant contact with theelectrolyte during rotation of the drum and are preferably disposed atremote ends of the electrolyte bath and are composed of a materialinsoluble in the electrolyte and free from electrolytic attack thereby.l have surprisingly found that excellent results can be attained whenthe conductive electrodes are constituted by the end walls of the drumand rotate therewith, the cylindrical drum wall forming the insulatingspacer for these electrodes. At least one but preferably both of theseend walls are provided with a passage for circulating the electrolytethrough the drum, the axial passage terminating in a fanlike array ofbores opening into the drum at the face of the end wall contacting theelectrolyte. The drum may further be provided, at least at regionsextending above the electrolyte level therein with apertures or ventsenabling evacuation of the gaseous products of the electrolyticdeburring of the workpieces.

Still another aspect of this invention resides in my discovery thatirregular deburring can be avoided by injecting an inert gas into theelectrolyte bath with the recirculating electrolyte stream. It appearsthat the inert gas creates labyrinthian paths for the electric currentflowing through the electrolyte, i.e. the ion mobility paths, therebydistributing the electrochemical action substantially uniformly. Thistechnique has the additional advantage that the inert gas upon evolutionfrom the electrolyte acts as a diluent for the nascent gases generatedby electrolysis and let off through the vents above the electrolytelevel. The inert gas may be admixed with the electrolyte in the bath orwith the liquid prior to its introduction into the tumbling drum.Furthermore, in accordance with the principles already discussed abovein general terms, I provide a magnetic flux radially through the drum,i.e. vertically when the drum is horizontal, preferably at a locationintermediate the electrode, to facilitate the agitation of theelectrolyte, the workpieces, and the carbon particles formingintermediate electrodes for the deburring action. These carbon particleshave an abrasive or semiabrasive character so that they mechanicallycooperate with the workpieces to supplement the electrochemicaldeburring by mechanical erosion of the rough surfaces. Thus the carbonparticles may be carbonaceous materials of relatively high hardness(e.g. synthetic diamond as produced by the system described in my U.S.Pat. No. 3,207,582 or the nondiamond but high-hardness carbon particlesobtained when synthetic diamond is made in accordance with thatprocess).

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view through a tumbling drum of adeburring apparatus in accordance with this invention;

FIG. 2A is an axial cross-sectional view of an electrode forming an endwall of the drum;

FIG. 2B is an elevational view thereof;

FIG. 3A is a cross-sectional view through a modified electrode;

FIG. 3B is an elevational view of this latter electrode;

FIG. 4 is a diagram of the electrochemical deburring system of thepresent invention;

FIG. 5 is a view similar to FIG. 1 of a modified system for deburringmetallic workpieces;

FIG. 6 is an axial cross-sectional view through a tumbling systemembodying other principles of this invention;

FIG. 7 is a diagram of a continuous deburring apparatus in accordancewith the principles of this invention;

FIG. 8 is an axial cross-sectional view through a deburring apparatususing a stationary system and diagrammatically showing theelectrolyte-circulating means therefor; and

FIG. 9 IS A cross-sectional view along the line lX-IX of FIG. 8.

In FIG. I, I show a rotary tumbling system for the deburring of metallicworkpieces in which a closed drum 1010 has a pair of end walls 1017 and1018 forming electrodes and retaining the electrolyte 1011 in the drum.Between the conductive electrodes 1017 and 1018, the drum is formed as anonconductive sleeve 1041 composed of or lined with electricallyinsulating material such as a hard rubber or an electrolyte-resistantsynthetic resin (e.g. a polyacrylate). Electrically insulating rubbergaskets 1042 are provided between the drum body 104] and the electrodes1017 and 1018. The drum may also be formed with a door 1045 to permitthe workpieces and intermediate electrodes to be introduced into theinterior of the drum. The electrodes IOI7 and 1018, which are inert tothe electrochemical action and to the electrolyte, are composed ofgraphite or an insoluble metal (e.g. stainless steel or monel). The drum1010 is mounted upon a pair of trunnions 1024a and 1024b extendingupwardly from a base 1026 and defining for the drum a horizontal axis.The drum is, in turn, carried by a pair of tubular shafts 1023a and1023b affixed to the respective electrode end walls 1017 and 1018 asdescribed in connection with FIGS. 2A, 2B and FIGS. 3A, 3B.

The drive means for the drum comprises a motor 1027 whose output shaft1028 is connected by a V-belt transmission 1030 with the hollow shaft102311 to rotate the drum about its horizontal axis. The electriccurrent for the electrochemical deburring operation is provided by apower supply 1019 and is applied via a pair of brushes 1019a and 1019bto the electrodes 1017 and 1018 via their shafts 1023a and 1023b.Electrolyte is circulated through the drum by a pump 1039 and acirculating system including an inlet pipe 1040 connected with thetubular shaft 1023b. The tubular shaft 1023:: leads electrolyte from thedrum to a return tube 1043 ending at a surface 1044.

The electrode 1017 and 1018 may be provided with a fanshaped array ofbores (FIGS. 2A and 2B) or a central array of mutually parallel bores(FIGS. 3A and 38), while means may be provided for injecting a gas intothe liquid-circulating stream (FIG. 5) and a magnetic field may beapplied in the radial direction (FIGS. 5 and 6). In the embodimentillustrated in FIG. 1, however, the end walls and electrodes 1017 and1018 are provided with axially extending bores 1017 and 1018'communicating with the hollow shafts 1023a and 1023b, respectively.

Within the drum, as described in my copending application Ser. No.598,391, I provide, in addition to the electrolyte 1011, a mass ofmetallic workpieces I012 (shown as rectangles) accompanied by conductiveparticles 1013 (hatched circles) and if desired magnetic and abrasiveparticles as described in copending application Ser. No. 598,391. Theelectrolyte may be any of the electrochemical machining solutiondescribed in applications Ser. Nos. 512,338, 535,268 and 562,857, allhaving been mentioned earlier. The particles 1013 are composed of carbonand act as intermediate electrodes. An important aspect of thisinvention resides in the fact that the carbon particles are formed ofrelatively highhardness carbonaceous material capable of withstandingmetallic abrasion in the tumbling of the workpieces. Suitable particlesmay be made by sintering pyrolytic carbon or by the electric dischargetechnique set forth in my U.S. Pat. No. 3,207,582. In addition, thecarbon particles may contain silicon carbide or the like abrasive powderdispersed therein prior to sintering. As a result, the electrochemicalaction is augmented by a mechanical smoothing of the workpiecesconcurrent with electrochemical removal of projecting portions of theworkpieces (i.e. burrs). The deburring power supply 1019 may be anyelectrolysis source as described in application Ser. No. 598,391 and theother applications mentioned earlier. Suitable sources may bealternating current, pulsating direct current or filtered direct currentas there described.

EXAMPLE 1 Using the system of FIG. 1, deburring was carried out in a l5percent sodium chloride solution upon a mass of 35 percent by volume ofsteel workpieces having a diameter of mm. and a length of 5 mm.Conductive particles, i.e. sintered pyrolytic graphite and siliconcarbide particles with a diameter of about 5 mm. were used in a ratio tothe workpiece quantity of about l.l5:l; it was possible to increase thedeburring rate over conventional systems using only aluminum oxideabrasive particles and a similar drum (diameter 300 mm., axial length of7 mm., electrolyte quantity 5 liters, current 80 amp), in terms of thequantity of material removed per unit time, from 10 to 30 times and theyield improved surface finish.

In FIGS. 2A and 23, I show a modification of the terminal electrode forthe drum of FIGS. 1, 5 and 6, the electrodes 1117 generally comprising adisk 11170 of graphite of other electrochemically inert materialattached at a flange 111712 to the tubular shaft 1123. A fanlike arrayof bores 1117c is formed in the disk 1117a and open at the inner face11l7d in contact with the electrolyte within the drum. From FIG. 28 itis apparent that the bores are distributed in conical arrays about axisof rotation of the drum (represented at 1125) so that a number of thesebores open into the drum above the liquid level (see FIG. 1) at each ofthe electrodes 1017 and I018. Thus gas forming above the electrolytepath can pass through the uppermost bores and can be entrained with theliquid stream leaving the drum and flowing to the reservoir 1044. Inthis reservoir, which is open to the atmosphere, the gases entrained inthe liquid can evolve into the atmosphere. The fanlike array of boreshas the additional advantage that, at

the inlet electrode (e.g. electrode 1018), the bores disperse the liquidand any gases entrained therein (FIGS. 5 and 6) to insure finedistribution of gas bubbles in the electrolyte bath and even deliversome gas above the electrolyte to act as a diluent for theelectrolytically evolve gases. The bores 1117c converge axially awayfrom the drum to communicate with the tubular shaft 1123 and thus form amanifold.

Electrode 1217 of FIGS. 3A and 38 represents a modified construction inwhich the disk 1217a is formed with a plurality of mutually spacedparallel bores 12170 which are located in the region of the center ofthe disk and communicating with the hollow shaft 1223 which is attachedto the disk 1217a at a flange 1217b. This embodiment has the dispersingadvantages mentioned in connection with the electrodes of FIGS. 2A and2B but does not evacuate gases from above the electrolyte level aseffectively. Either of the electrodes of FIGS. 2A and 2B and of FIGS. 3Aand 38 can be used in the drum deburring systems of FIGS. 1, 5 and 6.

In FIG. 4, there is shown a diagram of the principles of the presentinvention as discussed in greater detail in application Ser. No.598,39l. In this Figure, I show the workpieces 1012 as fortuitouslylocated between a pair of carbon particles 1013 and the electrodes 1017and 1018. If electrode 1017 is positive as shown for the purposes of theexplanation of this electrochemical phenomenon, it will be seen that aproximal carbon particle 1013 received an inducted charge so that itsregion juxtaposed with surface 1012 in the electrolyte 1011 acts as anelectrode to sustain electrochemical machining of this workpiecesurface. The random distribution of conductive particles and workpiecesbetween the electrodes is effective to insure practically uniformelectrochemical treatment of all workpiece surfaces.

However, burrs or other projections invariably lie at a shorter distancefrom one of the terminal electrodes or an effective intermediateelectrode than the other portions of the surface from which theyproject. The electrochemical machining current density is substantiallyhigher at these protuberances and machining preferably occurs in theseregions. Any mechanical smoothing is cumulative to the electrochemicalaction. It will be appreciated also that the presence of gas bubbles inthe electrolyte augments the machining action and its specific attackupon protuberances and the burrs. It has been found that the gas bubblestend to adhere to the surface of the workpiece in regions between theburrs and effectively insulate these regions while increasing thecurrent density at the burrs. This too improves the surface finish andcan be controlled by injecting inert gases into the system as wasdescribed in connection with FIG. 5. The term inert," however, must beconstrued in term of the activity performed here. When the evolved gasesinclude hydrogen, it will not be advisable to add oxygen and vice versa.Even normally active gases may be considered inert if they arenonexplosive when used in the presence of gases evolved from thedeburring bath.

In FIG. 5, there is shown a horizontal drum 1310 with a central body1341 held between a pair of gaskets 1342 and electrodes 1317 and 1318 ofthe type shown in FIGS. 2A and 2B. The electrodes are carried betweenthe tubular shafts 1323a and 132312 whose slip rings are in contact withbrushes 1319b and 1319a of the electrochemical machining power supply1319. A motor I327 drives the drum about its horizontal axis whileelectrolyte is circulated through the drum via a pump 1339 from thereservoir 1344 and a line 1340 communicating with hollow shaft 1323b.The electrolyte from the drum is returned via line 1343 to thereservoir.

In accordance with the principles of the present invention, gas isinjected into the electrolyte prior to its passage into the drum, thegas-supply source being shown at 1350 in FIG. 5. The source is a tank ofair, argon, carbon dioxide, nitrogen or the like which is connected viaa valve 1350a and a line 1350b with the hollow shaft 1323b of electrode1318. When the gas if forced under high pressure into the electrolytewhich, in turn, is under pressure of pump 1339, the liquid/gas mixtureentering the drum through the electrode 1318 expands to evolve the gasin the form of bubbl es and, in part, to induce some of the gas into thedrum above the electrolyte, thereby diluting the nascent gases releasedby electrolysis. The gas bubbles within the electrolyte adhere to theworkpiece surfaces and augment the deburring action. An electromagnet1315, whose flux can be represented by arrow (b is provided beneath thedrum 1310 and is effective to increase the electrochemical machiningaction.

As described in the copending application Ser. No. 598,391, the magneticfield may be of unidirectional or alternating type while the magnetitself may be stationary or reciprocating. The magnet may be energizedby a highfrequency AC source in addition to a low-frequency vibrating oroscillating source. The high frequency source preferably J operates at400 kHz. to 50 kHz. and endabove sonic frequencies while the lowfrequencies source operates at, say 30 to 40 Hz. It appears that themagnetic field has a two-fold action whereby it induces a dynamic flowof liquid electrolyte and secondly, imparts magnetically attractive orrepulsive motions to the workpieces when they are permeable.

In the system of FIG. 6, the drum 1410 has a cylindrical body 1441 whichis perforated to evolve gases and permit electrolyte to enter the drumas the latter is rotated in a bath 1435. A hood 1451 overlies the bath1435 and collects the evolved gases. Here too, the tumbling drum 1410has a pair of disk-shaped electrodes 1417 and 1418 which are insulatedfrom each one another by the gaskets 1442 although the electrodes arehere not perforated. Nontubular shaft 1423a and 142312 rotatably supportthe drum 1410 in a pair of trunnions 1424a and 1424b. The drive means isconstituted by a motor 1427 and a V-belt transmission 1430 connectingthis motor with shaft 14230. An electrolysis power supply 1419 applieselectric current to the electrodes 1417 and 1418 by the brushes 1419aand 1419b. A magnetic field is applied, as previously described, by thecoil 1415 in the vessel 1435.

FIG. 7 shows a continuous system for the deburring of metallicworkpieces wherein a succession of workpieces is deposited from a hopper1552 upon a belt 1553 which directs these workpieces to a perforatedendless belt 1510 which functions similarly to the drum of the precedingembodiments. The endless belt 1510, which has horizontal stretch 1510areceiving the workpieces 1512 from the conveyor 1553, passes over anidler pulley 1510b into the electrolyte bath 1511 in a vessel 1535 offunnel-shaped construction prior to emerging from the bath over afurther pulley 1510c. Within the vessel 1535, 1 provide agitating meansin the forming electromagnet 1537 which vertically displaces an armature1530 against a pair of compression 1538a to jumble the workpiece andcarbon particles contained on the stretch 1510d of the belt passingthrough the electrolyte bath. The armature 1538 carries a number ofrollers 1538b which support the belt in this region without frictionallyimpeding its movement.

Upon leaving the electrolyte bath 1511, the conveyor 1510 has ahorizontal stretch 1510c overhanging a collecting receptacle 1554 inwhich the deburring workpieces are caught, the band being then returnedto the horizontal stretch 1510a by downward stretch 1510f, a horizontalstretch 1510g and a vertical stretch 1510h.

Intermediate electrodes are formed by a mass of carbon particles 1513 aspreviously described. The carbon particles are retained in a supplytrough 1555 and are carried by a bucket conveyor 1556 to the vessel 1511where they are deposited upon the mass of workpieces entering the bath.The bank 1510 is, as previously indicated, perforated and has openingsthrough which the carbon particles may pass as they settle from theelectrolysis zone. Thus carbon particles which settle through the belt1510 are discharged at an outlet 1543 of the vessel and are collectedupon a sieve conveyor 1557 which carries them to the trough 1555. Theelectrolyte passing through the sieve conveyor 1557 is collected in thereservoir 1544 and recirculated by a pump 1539 and a line 1540 to thebath 1511.

The electrodes may, as described in Ser. No. 598,391, comprise verticalrods l518a, and 1518band 1518c which can be angularly oscillated aboutrespective vertical axes and vertically reciprocated by the mechanismshown for similar electrodes in the last-mentioned application. 1 havefound, moreover, that improved power utilization can be obtained when apolyphase power supply is available and the number of electrodes isequal n x P where P is the number of phases (usually three) available atthe supply and n is an integer. In this system, each phase is appliedbetween one pair of electrodes or the corresponding electrodes of a pairof sets, each set having it electrodes. in the simplified system of FIG.7, the power supply comprises a three-phase source 1519a which suppliesa conventional Y or A transformer diagrammatically represented at 1519beach of the output faces of which is applied across a pair of theelectrodes 15180 through 15180. The connections to these electrodes areshown both for Y and A systems although it will be understood that onlyone of these systems may be in use at any time. In the Y system, theneutral pole may be grounded at the transformer. This arrangementpermits each phase of a three-phase current to be effective and providesa greater effectiveness of the supply power without the expenserectifier systems which would be necessary to produce direct current andthe complex circuitry which would be necessary to convert thethree-phase force current to single-phase balanced current is operatingthe deburring device. lt has been found that the system is particularlydesirable when a large number of workpieces with a relatively largetotal volume is to be deburred at one time.

In FIGS. 8 and 9,1 show another embodiment of the present invention inwhich no continuously displaceable endless surface is provided and theagitation of the electrolyte, carbon particles and workpieces, iscarried out by means of pulsed jets or high-velocity streams ofelectrolyte directed tangentially into the vessel at the deburringregion. This system, while affording some mechanical smoothing bycontact of the workpieces with the carbon particles and the electrodesand walls of the vessel, primarily is effective to promoteelectrochemical removal of material from workpiece surfaces without anymovable apparatus members. The freedom of this system from vibrationaland rotational movement of electrodes, containers and the likeeliminates the need for drive motors journaling assemblies and the like,thereby making the entire apparatus more practical and less expensive,especially where small quantities of workpieces are to be treated.

In accordance with the principles of the present invention, theapparatus comprises a stationary vessel 1610 of electrically insulatingmaterial having an upwardly open pot-shaped chamber 1643 with anarcuately concave bottom 1643a. A pair of electrodes 1617 and 1618disposed at diametrically opposite locations along the inner wall of thechamber and energized by an electrochemical machining deburring powersupply 1619 of the character previously described. The vessel containsan electrolyte 1611 in which the workpieces 1612 (diagrammatically shownas rectangles) and carbon particles 1613 (diagrammatically shown ascircles) are distributed. The carbon particles 1613 are composed ofsintered carbon to which abrasive powder has been added and may be usedin conjunction with abrasive particles which contain no conductivematerial. When a number of pairs of electrodes are provided in thissystem, the considerations discussed in connection with FIG. 7 apply andthe power supply may include a polyphase-current source each phase ofwhich is connected across a respective pair of electrodes or arespective pair of electrode sets.

individually extend through thevessel 1610 and communicate via lines1640a... etc. with a pump 1639 drawing electrolyte from the reservoir1644. Electrolyte is returned to the reservoir via a line 1643'. Each ofthese lines is provided with a respective electromagnetically operablevalve 1659a,... etc., which successively pulse the electrolyte jetsintroduced into the vessel. Consequently, a vortex agitation of theelectrolyte is provided which dynamically coacts with gravitationalforce to produce the desired turbulence. When more turbulence isdesired, the jets can be pulsed in random sequence rather than insuccession as indicated. The deburring electrolyte may be admixed withinert gas (see FIG. from a cylinder 1650 and a valve 16500 which may beinjected into the electrolyte stream or may be added exclusively throughone of the inlet passages (i.e. passage 1623c in the system of FIGS. 8and 9).

EXAMPLE 2 A series of comparative tests were carried out with thestationary vessel arrangements of FIGS. 8 and 9, with a rotary vesselsystem and with a vibratory vessel system as described below. Theelectrolyte was an aqueous solution of percent by weight of potassiumnitrite and the workpieces were hexagonal nuts composed of iron and of 8mm. diameter. The nuts were of first grade 118 standard, black, class 4M8SS4lB-D with a total volume of 500 cc. The deburring elements added tothe system were carbon particles of 15 mm. diameter or abrasiveparticles of alumina or silica, each of 15 mm. diameter. When particleswere added, a total quantity of 2,000 cc. of such particles were used.The rotary system involved vibrations of L500 cycles per minute and thejet system made use of a electrolyte pressure of 5 and l5 kg. per cm).Four jets were employed in each case and the following tables give thetotal quantity of material removed in the deburring process, the voltageand amperage provided for the electrochemical action and the particlewear in percents by weight.

1. Rotary System Particle wear (per- Deburred Volt- Ampercent byquantity Particles age age weight) (grams) (a)... Carbon only 37 88 3 48(b). Carbon 60 vol. percent, 72 35 4 A110; 60 vol. percent. (0) A110; 60vol. percent, 90 0. 1 20 B101 50 vol. percent.

2. Vibratory System (a) Carbon only 30 80 5 42 (b). Carbon 50 vol.percent, 65 6 26 A110; 50 vol. percent. (c) A110; 50 vol. percent, 85 400.1 22

SlOi 50 vol. percent.

3. Jet Systen1wlth 5 kg./cm. electrolyte pressure (a). Carbon only 18 904 52 (b) Carbon 50 vol. percent, 46 60 3. 6 38 A1 0; 50 vol. percent.(c) A110; 60 vol. percent, 62 46 0. 2 26 S10; 50 vol. percent.

4. Jet System-with 15 lrgJcm. electrolyte pressure (11).-.. Carbon only16 100 3 56 (b)- Carbon 60 vol. percent, 48 62 4 39 A110; 50 vol.percent. (0) A110: 60 vol. percent, 71 40 0. 1 24 SiO; 60 vol. percent.

In addition, an electromagnet 1615 may be provided below the vessel asshown in FIG. 8 to augment the dynamic movement produced by the liquidjets by electromagnetically induced movements. It will also beunderstood that various combinations of the several systems may beprovided as well. Thus, the systems of FIGS. 1, 5 and 6 may providepulsed electrolyte jets to increase agitation while similar jets may beprovided in the system of HG. 7. A conveyor belt may be passed throughthe vessel of FIG. 8. The vessel of FIG. 8 may also be vibrated byelectromagnetic means as shown in H6. 7 or may cooperate with angularlyoscill aable and vertically reciprocable electrodes as there shown.

The invention described and illustrated is believed to admit of manymodifications within the ability of persons skilled in the art, all suchmodifications being considered within the spirit and scope of theappended claims.

I claim:

1. An apparatus for deburring an electrolysis soluble workpiece,comprising:

means forming a container for an electrolyte;

support means for positioning said workpiece with at least a surfacethereof in contact with the electrolyte within said container; supplymeans for introducing into said container a multiplicity of conductiveparticles to distribute them in contact with the electrolyte in theregion of said workpiece;

means for imparting random movement to said particles relative to saidworkpiece interspaced by the electrolyte;

and

means for applying an electric current through said electrolyte, saidparticles and said workpiece to solubilize electrolytically portions ofsaid surface against said particles functioning as counterelectrodes.

2. The apparatus defined in claim 1 wherein said support means comprisesa workpiece carrier for carrying said workpiece in an electrolyte, saidcontainer forming an enclosure around said support means for retainingthe electrolyte in the form of a bath.

3. The apparatus defined in claim 2 wherein said workpiece carrier is anelongated element, further comprising means for displacing said elementthrough said electrolyte.

4. The apparatus defined in claim 3 wherein said element is a conveyorband having a stretch for extending beneath the electrolyte level andstretches upstream of and downstream of the electrolyte for carryingsaid workpiece into said electrolyte and removing said workpiece fromsaid electrolyte.

5. The apparatus defined in claim 2 wherein said means for impartingrandom movement to said particles relative to said workpiece includesmeans for injecting gas bubbles into said electrolyte.

6. The apparatus defined in claim 2 wherein said means for impartingrandom movement to said particles relative to said workpiece includes anelectrolyte circulation system for displacing said electrolyte past saidsurface.

7. An apparatus for deburring an electrolyte-soluble metallic workpiece,comprising:

means forming a container for an electrolyte;

support means for positioning said workpiece with at least a surfacethereof in contact with the electrolyte;

means for distributing in the electrolyte a multiplicity of conductiveparticles;

means for agitating the electrolyte in contact with said surface toimpart random movement to said particles relative to said workpiece; and

means for applying an electric current to said electrolyte to solubilizeelectrolytically portions of said surface against said particlesfunctioning as counterelectrodes, said support means comprising aworkpiece carrier bearing said workpiece in the electrolyte, saidapparatus further comprising means forming an enclosure around saidsupport means for retaining the electrolyte in the form of a bath, saidmeans for retaining the electrolyte in the form of a bath said means fordistributing said conductive particles in said electrolyte comprisingconveyor means for entraining said particles in depositing them in saidelec trolyte.

8. The apparatus defined in claim 2 wherein said means for impartingrandom movement to said particles relative to said workpiece comprisesan oscillatory element coupled with said container, and means foroscillating said element.

9. The apparatus defined in claim 2, further comprising means forcontinuously separating said particles from said electrolyte bath.

10. An apparatus for electrolytically deburring a multiplicity ofmetallic workpieces, comprising:

a container for receiving a multiplicity of conductive particlesdistributed in an electrolyte;

a support means for positioning said workpieces in said container in theregion of said conductive particles and said electrolyte;

means coupled with said container for imparting random movement to saidparticles relative to said workpieces interspaced by the electrolytewithin said container; and

means for applying an electrochemical machining current through saidelectrolyte, said workpieces and said particles to electrolyticallysolubilize at least portions of the individual bodies of said workpiecesagainst said conductive particles functioning as counterelectrodes.

11. The apparatus defined in claim 10 wherein said support meansincludes a workpiece carrier for transporting said workpiecessuccessively past said region of said conductive particles and saidelectrolyte in said container.

12; The apparatus defined in claim 11, further comprising feed means forintroducing said conductive particles into said container.

13. The apparatus defined in claim 10 wherein said support meansincludes an elongated supporting surface for carrying said particles andsaid workpieces within said container while said random movement isimparted between them.

t i l 1

2. The apparatus defined in claim 1 wherein said support means comprisesa workpiece carrier for carrying said workpiece in an electrolyte, saidcontainer forming an enclosure around said support means for retainingthe electrolyte in the form of a bath.
 3. The apparatus defined in claim2 wherein said workpiece carrier is an elongated element, furthercomprising means for displacing said element through said electrolyte.4. The apparatus defined in claim 3 wherein said element is a conveyorband having a stretch for extending beneath the electrolyte level andstretches upstream of and downstream of the electrolyte for carryingsaid workpiece into said electrolyte and removing said workpiece fromsaid electrolyte.
 5. The apparatus defined in claim 2 wherein said meansfor imparting random movement to said particles relative to saidworkpiece includes means for injecting gas bubbles into saidelectrolyte.
 6. The apparatus defined in claim 2 wherein said means forimparting random movement to said particles relative to said workpieceincludes an electrolyte circulation system for displacing saidelectrolyte past said surface.
 7. An apparatus for deburring anelectrolyte-soluble metallic workpiece, comprising: means forming acontainer for an electrolyte; support means for positioning saidworkpiece with at least a surface thereof in contact with theelectrolyte; means for distributing in the electrolyte a multiplicity ofconductive particles; means for agitating the electrolyte in contactwith said surface to impart random movement to said particles relativeto said workpiece; and means for applying an electric current to saidelectrolyte to solubilize electrolytically portions of said surfaceagainst said particles functioning as counterelectrodes, said supportmeans comprising a workpiece carrier bearing said workpiece in theelectrolyte, said apparatus further comprising means forming anenclosure around said support means for retaining the electrolyte in theform of a bath, said means for retaining the electrolyte in the form ofa bath said means for distributing said conductive particles in saidelectrolyte comprising conveyor means for entraining said particles indepositing them in said electrolyte.
 8. The apparatus defined in claim 2wherein said means for imparting random movement to said particlesrelative to said workpiece comprises an oscillatory element coupled withsaid container, and means for oscillating said element.
 9. The apparatusdefined in claim 2, further comprising means for continuously separatingsaid particles from said electrolyte bath.
 10. An apparatus forelectrolytically deburring a multiplicity of metallic workpieces,comprising: a container for receiving a multiplicity of conductiveparticles distributed in an electrolyte; a support means for positioningsaid workpieces in said container in the region of said conductiveparticles and said electrolyte; means coupled with said container forimparting random movement to said particles relative to said workpiecesinterspaced by the electrolyte within said container; and means forapplying an electrochemical machining current through said electrolyte,said workpieces and said particles to electrolytically solubilize atleast portions of the individual bodies of said workpieces against saidconductive particles functioning as counterelectrodes.
 11. The apparatusdefined in claim 10 wherein said support means includes a workpiececarrier for transporting said workpieces successively past said regionof said conductive particles and said electrolyte in said container. 12.The apparatus defined in claim 11, further comprising feed means forintroducing said conductive particles into said container.
 13. Theapparatus defined in claim 10 wherein said support means includes anelongated supporting surface for carrying said particles and saidworkpieces within said container while said random movement is impartedbetween them.